Carburetor



. June 17, 1941. s. F. HUNT 2,245,672

GARBURETOR y Filed Sept. 17, 1934 2 Sheets-Shet 1 Z 5g 42\g llljs 45g l41ow /4 0 1 47 E! r 171g/ "4: if 4" 6 Y f 48 Engg., i

54 lxl 1' /4 26 KSULWr/O/'Y Z 6^ v JNVENTOR.

June 17, 1941. 5 HUNT 2,245,672

CARBURETOR 'Filed sept.l 17, 1954l 2 sheets-sheet 2 im? E l C: CUIT 59;

INVENTOR. 66071 F HUNT ATTORNEY.

`Parental June 11, 1941 2,245,672 caminamos Scott F. Hunt, South Bend,Intl," assignor to Bendix Products Corporation, South Bend, Ind., acorporation of Indiana Application September 17, 1934, Serial No.744,329

2z claims.

This invention relatesfto carburetors, and more particularly to meansfor controlling the choke valve of carburetors, so as to furnish themost economical and efficient combustible mixture to the engine.

'The richness of the mixture supplied by the I carburetor is usuallycontrolled by varying the quantity of air admitted to the carburetor, bymeans of a choke valve which operates to vary the effective area of theair inlet passage.

It is desirable to control the choke valve auto= matically, in such amanner that the carburetor will supply a rich mixture when the engine isco1d,'and a progressively leaner mixture as the engine warms up tonormal operating temperature.

This invention is an improvement upon the device disclosed in Patent2,071,633, issued February-23, 1937, to the present applicant, and inits preferred form covers an automatic choke mechanism constituting animprovement on that dis-L closed in Patent No. 1,945,191, issued January30, 1934, to the present applicant. The device hereinafter disclosedincludes a carburetor having an unbalanced choke valve, urged toward itsopen position by the force of the air entering'l the air inlet passageand impinging on the unequal areas of the valve on either side of thechoke shaft. The force of gravity acting on the unbalanced choke valvealso tends to open the valve.

The choke valve is yieldingly urged toward the closed position-by athermostatic element which exerts on the choke valve a force which isdependent upon the temperature of the thermostat. When the engine beginsto operate under its own power, an electric current is passed through aresistance coil, placed in juxtaposition to the thermostat. Thethermostat becomes heated by the coil and exerts a decreasing forceurging the choke valve toward closed position.

The resistance'coil placed in juxtaposition to 'the thermostat iscontrolled by the engine ignition la compact and serviceable unit of theclass deseveral views:

scribed, which will be less susceptible to maladjustment and failure inservice, and economical to manufacture.

Other objects and advantages of the invention will beapparent from thefollowing description. taken in connection with the accompanyingdrawings, submitted for purposes of illustration only,

- and not intended to denne the scope of the invention, reference beinghad for that purpose to the subi oined claims.

In the drawings, wherein similar reference nu-4 merals refer to similarparts throughout the.

Figure 1 is a longitudinal view, partly in section of a carburetorequipped with a device of the present invention;

Figure Z is a view taken on the line 2-2 of- Figure 1, looking in thedirection of the arrows: Figure 3 is a view taken on the line 3-3 ofFigure 1, looking in the direction of the arrows;

Figure 4 is a diagrammatic view showing the electric circuits of thedevice;

Figure 5 is a view, partly in section, showing one type of automaticswitch operating mecha-` nism;

Figure 6 is a sectional view of a modified form of switch operatingmechanism wherein engine` exhaust pressure is employed to close thecircuit;

Figure 7 is a sectional view of a further modication, showing athermostatically operated switch; v

Figure 8 is a sectional view of a further modification wherein manifoldvacuum is employed to actuate an electric switch; and

switch, and by a switch automatically closed only during engineoperation. I A

An object of this invention', is, therefore, to

provide an improved means for controlling the4 choke valve of acarburetor in accordance with vide electric means for heating thethermostat operable only upon engine starting. Y,

' Another object of the invention is to provide Figure' 9 is adiagrammatic view of a further `modification disclosing an electricallyoperated relay. e

Referring more particularly to Figure 1, there is shown for purposes ofillustration, a downdraft.

plain tube carburetor, having an air inlet passage Iii communicatingwith a main carbureting passage i2. The air inlet passage Il isadiustablyl controlled by an unbalanced choke valve Il, fixed to a chokeshaft Il. The choke valve il is provided with a spring pressed poppetrelief valve it, to permit a small amount of air to bypass the chokevalve under certain operating condi- -I tions.

The main carbureting passage I2 is tted with a secondary venturi 2t,into the most restricted section of which a primary venturi 22discharges. 'I'he primary venturi is supported by a iin (not shown)extending from the walls of the main carbureting passage. A main fueldischarge nozzle 24 is positioned in the most restricted section fueldischarged from the fuel nozzle 24, and the air entering the air inletpassage I0, is controlled by a throttle valve 26, xed toa throttle shaftlll. When the throttle valve 28 is closed, fuel for idling purposes isfurnished from the fuel reservoir 26, by a duct 32 terminating in anidling nozzle 54, posterior to 'the throttle valve 26. Air for idlingpurposes is supplied through a passage I6, anterior to the throttlevalve 26, and communicating with the passage 34. An idling adjustmentscrew 38 is provided, by which the quantity of combustible mixturebypassing the throttle valve 26 may be adjustably controlled.

The choke valve I4 is actuated in the closing direction by athermostatic element 40, housed within a chamber 42, formedby a flatplate 44 and a metal casing 46. The chamber 42 may be heat-insulated inany suitable manner, if -desired. The choke shaft I6 projects throughthe plate 44 and is fixed to the inner end of a spiral thermostat 40 insuch a manner as to be insulated therefrom, as shown, and actuatedthereby. The metal casing 46 is provided with an insulated terminal 48,to receive one end of an electric wire 61. An electric resistance coil52 is xed on the inside of the casing 46 in heat exchange relation tothe thermostat 46 and is separated from the casing 46 by an insulatingmember 41. A snap contact member 54 is connected with one end of theresistance coil 52, and bears against the inner end of the thermostat 45in electrical conducting relation. The outer end ofthe thermostat 4|! isformed in the shape of a hook, to engage a stop member 56, fixed in theplate 44 so as to form an electrical connection or ground circuittherewith. f

As described hereinafter, the thermostat 46 is heated electrically whenthe engine begins to operate on its own power, and the circuit is brokenwhen the thermostat -becomes heated and uncolls, thereby moving thehooked end outof contact with the stop member 56, to break the electriccircuit through the resistance coil 52.

Figure 4 illustrates the relation of the electric f circuits ofthedevice to those of an internal combustion engine. Electric current issupplied by a storage battery represented at 58. through the wires 60,6| and 62 when an ignition switch 63,

but when the speed of the engine increases, an engine-operated generator66 supplies the current. The generated current is passed through a lead'65 to a solenoid 16 comprising a resistance coil 1I wound upon a core12. When the voltage of the generated current is greater than thatsupplied by the battery 56, the solenoid 1l will become energized anddraw an arm 1I toward the core 12, whereupon a movable contact point ism'oved into engagement with a fixed contact point 111, in the knownmanner. The generator 68 then furnishes the current for. theigniinterposed in the wire 6|, is closed, to the ignition circuit 59.When the ignition switch 63 is closed and the engine is started, anengine-operated auxiliary switch, having a movable contact member 64,and a xed contact member 65, is closed by automatic switch operatingmechanism 66 described hereinafter, whereupon an electric current flowsthrough the wire 61 to the resistance coil 5 2, to heat the chamber 42and the/thermostat 40. As the thermostat 46 becomes heated, it will tendto uncoil, thereby exerting a decreasing force tending to close thechoke valve I4, and finally uncoiling to such an extent that I thehooked end disengages the stop member 56,

thereby breaking the electric circuit and discontinuing the flow ofcurrent through the resistance coil 52.

When the engine is operating below a predetermined speed, the currentpassing through the resistance coil 52 is supplied by the battery 56,

tion circuit and the resistance coil 52, through a wire 16 connected tothe fixed contact point 11 and the wire 6I. Any excess current suppliedby the generator 68 is passed through the battery 56 as a chargingcurrent inv the usual manner. When the voltage of the generated currentis less than that supplied by the battery 56, as when the engine isstopped, the solenoid 16 becomes deenergized, whereupon a spring 51moves the arm 'I3 to -the rightlas viewed in Figure 4, to move thecontact point 15 away from the xed contact 11 to interrupt the currentflowing from y the generator 66.

Since it is desirable that the hea-ting of the thermostat be effectedproportionately to the heating of the engine, the flow of currentthrough the resistance coil -52 is started only when lthe engine isactually running, and not merely when f the ignition switch is turnedon. If the heating of the resistance coil began immediately upon turningthe ignition switch, the thermostat 46 might permit the choke valve I4to open before the engine had started, if it failed-to start promptly,or if the operator failed to actuate the starting mechanism (not shown)promptly upon turning the ignition switch.

To obviate this diiliculty the present invention incorporates anauxiliary switch having movable and fixed contact members 64 and 65respectively,A operable automatically upon engine starting, by a switchoperating mechanism 66.

Figure 5 illustrates one type of switch operating mechanism 66 whereinoil pressure developed by a conventional oil pump represented at 14, isi employed to actuate a piston 16, in a cylinder 16, to move a lever 66operably connected to the piston 16 by a rod 62. The lever 66 carriesthe mov able contact point 64, which engages the 'fixed contact point 65when the piston 16 is actuated, thereby closing an electric circuitthrough the resistance coil 52. When the oil pressure drops below apredetermined value, as when the engine is stopped. a spring 66 returnsthe/piston 16 to its inoperative position, wherein the contact points 64and 65 are separated.

Figure 6 shows an arrangement wherein exhaust pressure is employed toclose the heating circuit.y An unbalanced valve /96 is mounted in theexhaust pipe 92. When'the engine is operating, the pressure of theexhaust gases rotates the valve 96 in the counterclockwise direction,thereby rotating an arm 94, fixed thereto, to exert tension on a link66, operably connected to `a crank to move the contact points 64 and 65position started, the thermostatic elementl |04, subjected to the heatof the exhaust gases, becomes deformed, and moves to the positionindicated in dotted lines, whereby the movable contact. member 64engages the fixed contact member 65 to close the circuit through theresistance coil 52 of Figure 4. When the engine has stopped and coolsdown, the thermostatic element IM returns to its original position toyseparate the contact points 64 and 65 to break the circuit through theresistance coil 52.

Figure8 illustrates an embodiment wherein the vacuum developed in theengine manifold IH is applied through a pipe H to lone end of a cylinderII2. When the engine is operating, the pumping action of the engine (notshown), is exerted in the cylinder H2 to move a piston IM to the left,thereby compressing a spring H6. The piston rod IIB and the connection|20 move the contact point 64 into engagement with the contact point 65`to close the circuit and heat the thermostat 40. When the engine isstopped, the spring H6 moves the contact point 64 away from the fixedpoint 65 to break the circuit through the resistance coil 52.

The embodiment shown 'in Figure 9 is similar in many respects to thatshown in Figure 4, and corresponding parts have therefore been givencorresponding reference numerals. When the voltage generated by thegenerator 68 is higher than that supplied by the battery 58, thesolenoid 10 will become energized, thereby drawing the arm 13 in contactwith the core 12 of the solenoid, and also moving the contact point 64.into engagement with the fixed contact point 65 to close the circuitthrough the resistance coil.52. When the generated voltage drops, aswhen the engine is stopped, the spring 51 moves the arm 'I3 out ofcontact with the core 12 of the solenoid 10, and moves they contactpoint 64 away from the fixed contact65 to break the heating circuitthrough the coil 52.

The invention thus comprehends a device in which an unbalanced chokevalve is urged toward the closed position by a thermostat when cold, andheating means Ioperate only when the engine has started running and thethermostat is exerting'a 'force on the choke valve, to graduallydecrease and nally to eliminate the force of the thermostat on the chokevalve. The choke valve will then be moved to the full open by thecombined force of gravity acting on the unbalanced valve, and the forceof the air entering the air inlet passage I0. As long as the enginecontinues to run, the'choke valve will remain in the full open position.When the engine is stopped and cools ofi, the thermostatwilllmcoil untilthe,hooked end of the thermostat engages the stop member 56, whereuponit will exert a force on the choke valve, urging it toward the closedposition. No current will flow through the resistance coil 52, however,until the rengine is started.

Although the invention has been described with particular reference tolthe embodiments shown in the drawings, it is to be understood that itPmay bel embodied lin other forms and is not .limited except by the termsofthe following claims. i

I claim: "1. InA aT carburetor for an internal combustion engine havingan electric ignition system -lncluding a generator to supply electriccurrent,

a main induction `passage inthe carburetonan. unbalanced choke valvepivotallymounted inA the induction passage, thermostatic means urgingthe choke valve closed when cold, and electric heating means adapted toheat the thermostat to decrease the force of said thermostat `when theengine is started and electric current is supplied 'by the generator.

. 2. In al carburetor for an internal combustion engine havinganignition circuit, means for control-ling the inflow of air to thecarburetor, temperature responsive means for actuating said controllingmeans, and electric means in said ignition circuit operable only whenthe engine is operating for varying the force of said temperatureresponsive means.

3. In a carburetor having an air inlet passage, a choke valvecontrolling the ilow of air into said passage, temperature responsivemeans controlling the choke valve when cold, electric means forcontrolling the action of the temperature responsive means, saidelectric means being operative only after the engine has been started,and

substantial reduction in pressure in the main carbureting passageposterior to said throttle valve.

5. In a carburetor having a main carbureting passage, an unbalancedchoke valve, a throttle valve, a thermostat urging the choke valveclosed when cold, electric means operable to control the action of thethermostat only upon a substantial reduction in pressure in the maincarbureting passage posterior to said throttle valve, vand means tointerrupt the action of the `electric means when the thermostat ceasesto urge the choke valve closed.

6. In a carburetor for an internal combustion engine having an electricignition system, an ignition switch, an oil pump, an oil pressureactuated motor, an electric switch operable by said motor,a maininduction passage in the carburetor, an unbalanced choke valve in theinduction passage, temperature responsive means urging the choke valveclosed when cold, and electric means to control the action of thetemperature responsive means, said electric means becoming operable uponclosing both the ignition switch and the oil pressure operatedelectricswitch.

7. In a carburetor for an internal combustion engine having an electricvignition `system, an ignition switch, an oil pump, an oil pressureactuated motor, an electric switch operable by said motor, a maininduction passage in the carburetor, an unbalanced choke valve-in theinduction passage, temperature responsive means urging the choke `valveclosed when cold, electric means to modify the action of the temperatureresponsive means, said electric means becoming operable `upon closingbothp the ignition switch and the oiL pressure operated electric,v y

switch, and means to interrupt the action of the electric means when thetemperature responsive means ceases to urge the choke valve closed.

' 8. In a carburetor for an internal combustion engine having anelectric ignition system, an

ignition switch, an intake manifold constituting a source of vacuum whenthe yengine is running, an electric switch, a vacuum vactuated motoradapted to close lsaidswitch when the vacuum in the intake manifoldreaches a predetermined value, a main .carbureting passage, anunbalanced choke valve mounted in the carbureting passage, temperature`responsive a main carbureting passage, an unbalanced choke valvemounted in the carbureting passage, temperature responsive means urgingthe. choke valve closed when cold electric means to control the actionof the temperature responsive means, said electric means becomingoperable upon closingboth the ignition switch and the vacuum motoractuated electric switch, and `means to interrupt the action of theelectric means when the temperature responsive means ceases lto urge thechoke valve closed.

10. In a carburetor for an internal combustion engine having an electricignition system, an ignition switch, a generator, a generator operatedlelectric switch, a main carbureting passage, anunbalanced chokevalvemounted in the carbureting passage, temperature responsive means urgingthe. choke valve closed when cold, and electric means to modify theaction of the temperature responsive means, said electric means becomingoperable upon closing both the ignition switch andv the generatoroperated electric switch. ll. In a carburetor for engine having anelectric ignition system, an ignition switch, a generator, a generatoroperated electric switch, a main carbureting passage, an unbalancedchoke valve mounted in the carbureting passage, temperature responsivemeans urging, the choke valve closed when cold, electric heating meanscontrolling the action of the temperature responsive means, said heatingmeans becoming operable upon closing both the ignition switch` andgenerator operated electric switch, and means to interrupt the action ofthe heating means when the temperature responsive means ceases to urgethe choke valve closed.

12. In a carbln'etor for an internal combustion engine having anelectric ignition circuit,

an igition switch, an electric switch, means operative only duringengine operation for closing said switch, a main induction passage inthe carburetor, an unbalanced choke valve in the induction passage,temperature responsive means urging the choke valve closed. when cold,elec#- t'ric means to modify the action of the tempera.'- tureresponsive means, said electric meansbecoming operable upon closing theignition switch. and the closing of the first mentioned switch.

13. In a carburetor for an internal combustion engine having anelectricignition circuit, an igition switch, and an electric switch `meansoperlative only -during engine'operation for closing said switch, a maininduction passage in the carburetor, an unbalanced choke valve in theinducf tion passage. temperature responsive means urging the choke valveclosed when cold', electric means to modify the action .of thetemperature an .internal combustion responsive means, said electricmeans becoming operable upon closing of both the ignition switch and theilrst mentioned switch, and means to interrupt the action of theelectric means when the temperature responsive means ceases to urge thechoke valve closed. I

14. In a carburetor for an internal combustion engine having a source ofpressurewhen the engine is running, an induction passage, achoke valvecontrolling the flow of air into the induction passage, thermostaticmeanscontrolling the choke valve, a casing sun'ounding the thermostat,electric heating means inthe casing adapted' to heat the thermostatunder certain operating conditions, and'switch means operable by saidsource of pressure to initiate a ilow of electricity through the heatingmeans when the engine is started,

15. In a carburetor for an internal vconfxbustion engine having anignition circuit including a generator' adapted to supply'electriccurrent, a main vinduction passage, an unbalanced choke valve adapted tocontrol the ilow of fluid into the induction passage, a thermostatadapted to urge the choke valve toward the closed position at lowtemperature, a casing surrounding the thermo- A stat, an'el'ectricheating coil in the casing, a

stop member in the casing adapted to receive one end oi' the thermostat,insulating means between the stop member and the thermostat, insulatingmeans between the thermostat 'and the choke valve, and means including aswitch adapted to initiate a ilow of current to the heating coil whenthe engine has started and a predetermined flow 'of current is suppliedby the generator.

16. In a carburetor for an internal combustionv engine having anignition circuit including a generator adapted to supply electriccurrent, a main induction passage, an unbalanced choke valve adapted tocontrol the flow of fluid into the induction passage, a thermostatadapted to urge the choke valve toward the closed vposition at lowtemperature. a casing surrounding the thermo stat, an electric heatingcoil in the casing, a stop member in the casing adapted tno receive oneend of the thermostat, insulating means between the stop member and thethermostat, insulating means between the thermostat and the choke valve,and means including a switch adapted to initiate' a iiow of current tothe heating coil when the engine has started and a predetermined flow ofcurrent lis supplied by the generator, and means to interrupt the flowof current to the heating coil when` the thermostat ceases to con- .trolthe choke valve.

17. In a carburetor for an engine having means l .to supply pressure toav uid when the engine valve to the closed position at low temperatures,

a casing surrounding the thermostat, electric heating means in thecasing adapted to heat the thermostat, switch operating means adapted tosupply electric'current to the heating means upon the existance of apredetermined pressure in the pressure source, and insulating means tointerrupt the flow of electric current to the heating means when thethermostat ceases to control the choke valve.

18. In a carburetor having an inductionpassage, a choke valvecontrolling the inilow ofi air to said passage, temperature responsivemeans influencing the movements of the choke valve,

heating means becoming operative only when the engine is operating, andbecoming inoperative when the temperature responsive means reaches apredetermined temperature. ,l

19. A choke mechanism -for the charge forming device of an internalcombustion engine having in combination means for varying the fuel toair ratio in the mixture formed by said charge forming device comprisinga choke valve for closing the air intake of saidcharge forming device,thermally` responsive means for operating said valve, means other thanthe'engine but.

rendered operative when the engine` begins to run under its own powerfor heating the thermaily responsive means, and means for renderingsaidlast named means inoperative.

20. A choke mechanism for the charge forming device of an internalcombustion engine having in combination means `for varying the fuel toair ratio in the mixture formed by said charge forming device, thermallyresponsive means for operating said ratio varying means, means otherthan the engine but rendered operative when the engine begins to rununder its own power for heating the thermally responsivev means, andmeans operable by the thermally responsive means for rendering theheating means inoperative. l.

21. A choke mechanism for the charge forming device of an internalcombustion engine having in combination means for varying the fuel toair ratio in .the mixture formed by said charge forming device,thermally responsive means for operating said ratio ying means,relatively remotely located wit respect to the engine. heating means forraising the temperature adjacent the thermally responsive means morerapidly than the temperature adjacent the ensine is raised and meansoperable by the thermally responsive means itself for rendering theheating means inoperative after a predetermined eft'ect on saidthermally responsive means.

22. A choke mechanism for the charge forming device of an internalcombustion engine having in combination means for varying the fuel toair ratio inlthe mixture formed by said charge forming device, athermostat for operating said ratio varying means, an electric heatingdevice ing device inoperative.

for heating the thermostat, a generator, means operable by the generatorfor causing said heating device to become operative; and means operableby the thermostat for rendering the heat-

